Automatic two directional belt training idler assembly



March 1966 R. F. LO PRESTI 'ETAL 3,240,321

AUTOMATIC TWO DIRECTIONAL BELT TRAINING IDLER ASSEMBLY 2 She ets-Sheet 1 Original Filed July 13, 1959 March 15, 1966 R. F. LO PRESTI ETAL AUTOMATIC TWO DIRECTIONAL BELT TRAINING IDLER ASSEMBLY 2 Sheets-Sheet 2 Original Filed July 13, 1959 INVENTORS. my A w 7567/ BY JW/A/ z mw/m pz/h/ ffw/a/ ///W/// Q ww m a llllllllll w ifu w. M N w m llill I IIL mi|\ T I|l|lll\ M ew I I United States Patent Office 3,240,321 Patented Mar. 15, 1966 2 Claims. Cl. 198202) I This is a continuation of application Serial No. 826,528, filed July 13, 1959, now abandoned.

This invention relates to flexible belt conveyors, and particularly to two directional automatic belt training troughing idler assemblies for use in such conveyors. For further reference to a type of flexible belt conveyor with which the present invention is especially, though not exclusively, intended for use reference is made to the Craggs and McCann Patent No. 2,773,257.

Belt training in flexible belt conveyors is a constant problem, particularlywhen the conveyor is subjected to rugged operating conditions as in underground coal mines. De-training of the belt materially reduces its carrying capacity, unnecessarily frays its edges and sets up stresses and strains in the system which requires increased power and often .leads to early failure of components.

It has been found that the roller assemblies impart atrainingeffect to the. belt which is directed substantially perpendicular to the axes of the rollers. It has been found further that this training effect can be controlled by adjusting the position of the assemblies with respect to the belt. If the outer end of the wing rollers for example is canted inwardly toward the belt in the direction of belt travel the training effect exerted by the roller tends to center thebelton the assembly. Similarly, if the outer end of a wing roller is canted outwardly from the belt with respect to the direction of belt travel, that is upstream, the' belt tends to detrain and may move laterally off the roller assembly.

Various systems have been devised to maintain the belt trained, but most'require additional equipment whose only purpose is to train the belt. This additional equipment increases the cost and complexity of the system, complicates installation, and increases maintenance problems. Further, some systems can only exert a training influence on the belt when the belt runs in one direction. It isoften desirable that a beltrun in both directions, and train when running in both directions, and in these instances the uni-directional training arrangements do not fully satisfy the need. Further, some of the known arrangeme nts are substantially ineffective to train a conveying belt when the conveyor runs uphill, or at least of reduced effectiveness. In other arrangements the positiveness of the training action may be affected by shock loads hitting the roller assemblies. V

In still other roller assemblies, for example those in which the training effect is derived in some measure from a variation in contour of the rollers, the frictional forces between theconveyor belt and the rollers may be so great as'to wear the belt at a much too rapid rate. Finally, in some prior art arrangements the ability of the training roller assemblies to be shifted from one position to another is substantially uno-btainable, especially when using the relatively thin, relatively flexible belts of the type extensively employed in the underground coal mining industry.

Accordingly, the primary object'of this invention is to provide a two directional training roller assembly which automatically trains the conveyor belt passing thereover solely by the action of the belt on the roller.

Another object is to provide a two directional roller assembly which automatically trains the conveyor belt by creating a differential drag effect on the wing rollers which swings the wing roller or wing rollers affected into a training position in response to passage of the belt thereover in a detrained condition.

Another object is to provide a two directional training roller assembly having at least a limited troughing movement which automatically trains the conveyor belt.

A further object is to provide an automatic two direetional cradle type roller assembly having a tension path extending from strand to strand through the center roller which bypasses the wing rollers to thereby leave them free to cant forwardly and rearwardly in the direction of belt travel.

Yet a further object is to provide an automatic two directional semi-cradled training roller assembly particularly adapted for downhill and uphill installation which maintains the center roller substantially perpendicular to the conveyor side frames and eliminates pendulum movement of the center roller or rollers about the sideframes.

Yet a further object is to provide an automatic two directional belt training troughing assembly which is equally effective to train a belt whether the belt runs uphill or downhill.

Yet another object is to provide a two directional belt training troughing idler assembly in which shock-s imparted to the assembly, such as a point load striking the assembly, Will not cause the training rollers to move from their training position.

Yet a further object is to provide an automatic belt training troughing idler assembly which is an ideal combination of training ability, horsepower requirements, and belt Wear.

Another object is to provide an automatic two directional belt training troughing idler assembly which is especially suited for rubber belts, or belts having the characteristics as to fiex-ure, compressibility and texture of rubber, such as neoprene or the recently introduced plastic belts.

Yet a further object is to provide an automatic two directional belt training troughing roller assembly in which the wing rollers exert enough differential drag to positively move the wing rollers downstream when the belt is running empty, but, at the same time, produces insuflicient drag to require an excessive increase in horse power when the belt runs loaded.

- peded by the action of gravity.

Further objects and advantages of the invention will become apparent from the following description of the invention when read in light of the accompanying drawings wherein by way of illustration and example certain embodiments of the invention are set forth.

The invention is illustrated more or less diagrammatically in the accompanying drawings, wherein:

FIGURE 1 is a top plan view of a three roller troughing roller assembly embodying the principles of the invention;

FIGURE 2 is a view taken substantially along the line 22 of FIGURE 1 looking perpendicularly at the end of the roller assembly;

FIGURE 3 is a top plan view of another embodiment of the invention;

FIGURE 4 is a sectional view taken substantially along the line 4-4 of FIGURE 3 and with certain dimensions exaggerated for purposes of description.

FIGURE 5 is a top plan view, partially diagramatic, of another embodiment of the invention.

Like reference numerals will be used to referto like 3 parts throughout the following description of the drawings.

A troughing idler assembly embodying the principles of the invention is indicated generally at in FIGURE 1. The assembly is suspended from a pair of conveyor side frames 11 and 12 which, in this instance, are wire ropes. It should be understood, however, that within the scope of the invention other types of side frames might be employed.

The troughing idler assembly consists of a roller assembly, indicated generally at 13, which comprises a pair of wing rollers 14 and 15 flanking a center roller 16. Although a three roller troughing idler assembly has been shown it should be understoodthat within the scope of the invention a greater number of rollers may be employed and the illustrated embodiment is chosen solely for convenience of description. The illustrated embodiment is commonly referred to in the trade as a semi-cradled idler assembly.

The wing rollers 14 and 15 are supported by and swingable with respect to cradle frames 17 and 18 respectively. Cradle frame 17 consists of inner end plate 19, a pair of outwardly diverging side frame members 20 and 21, and an outer arcuate end plate 22. Similar reference numerals followed by the subscript a refer to similar parts in right cradle frame 18 where necessary to a complete understanding of the invention since the component parts are substantially identical from cradle to cradle.

Shaft of center roller 16 is connected to the inner end plates 19, 19a, of the side cradles by ears 26 and pivot pins 27. In this instance the cars 26 are shown substantially perpendicular to the plane of the belt to confine flexing movement of the center roller with respect to the wing rollers to a plane generally perpendicular to the belt.

The inner ends of the wing rollers are connected to the inner end plates 19, 19a, by ears 28 and pivot pins 29 passing through the ears and roller shafts 30, 30a. The horizontal ears 28 are perpendicular to ears 26 with the result that movement of the wing rollers in a plane perpendicular to the belt is substantially prevented, yet the wing rollers are free to swing in the direction of belt travel about pivot pins 29, 29a, in a plane substantially parallel to the plane of the conveyor belt.

Slideways 32, 32a, and end plates 22, 22a, provide a limited arcuate canting movement of shafts 30, 30a. Slots 33, 33a, provided easy insertion and removal of the shafts. As best seen in FIGURE 2, the slideways are planar and parallel to the angle of inclination of the conveyor. Thus if the conveyor is installed on level ground the slideways will be level. Each end plate 22, 22a, is connected to pivotal hooks 34, 340, or other connecting devices which are secured by wedges 35 or similar means to the wire rope side frames.

In this instance the Wing rollers are. formed with a uniformly decreasing taper from their inner towards their outer ends, the taper being on the order of about 2. When the belt 36 moves in the direction of the solid arrow the wing rollers assume their illustrated full line position. When the belt travels in the direction of the dotted arrow, the wing rollers assume the indicated phantom line position.

Another embodiment of the invention is illustrated in FIGURES 3 and 4. In this embodiment the troughing idler assembly 40 is of the fully flexible type. That is, theroller assembly 41 which consists of wing rollers 42 and 43 flanking the center load carrying roller 44 are not supported in a frame assembly. Rather, load on the assembly is transmitted directly through the Wing roller shafts which are articulately connected one to the other for flexing movement in a generally vertical plane. Link assemblies 45, 46, and suitable connecting devices 47, 47a, connect the assembly to the rope side frames 11 and 12. In "this instance the rollers are connected one to another for flexing movement in a generally vertical plane whereas the link assemblies 45, 46 are generally vertically axised so that the assembly can swing in a plane generally parallel to the plane of the belt. In the FIG- URE 3 position the conveying reach of the belt 36 has detrained to the right, the outer end of right wing roller 43 has moved downstream with respect to its inner end and the balance of the assembly, and the link assembly 46 has swung about its outer pivot 48 to accommodate the shifting movement of the roller assembly.

Another embodiment of the invention is illustrated in FIGURE 5. In this embodiment, as in that described in FIGURES 1 and 2, the wing rollers 50, 51 are carried by and swingable with respect to semicradles 52, 53, which in turn are connected to the center roller 54. The wing roller dead shafts are again free to swing along horizontal slideways 32, 32a.

In this instance, however, the contour of the wing rollers differs considerably over that of the contour shown in FIGURE 1. Here the inner ends of the wing rollers have been diametrically expanded over only a portion of their length. Referring to Wing roller 50 for example, only approximately the inner fifth of the roller, indicated by the reference numeral 55, is of a differing diameter. The balance of the roller is of a uniform diameter.

The expanded diameter portion can be formed in several Ways. Since the rollers are generally formed from tubular stock the outer ends can be sealed and the inner ends subjected to hydraulic pressure which expands the rollers. Alternately, and perhaps most efficiently, the inner ends of the rollers may be expanded by forcing a mandrel into the ends of the rollers during production, either cold or with the aid of heat. It will be understood that the roller shell is generally composed of rather thin stock which may, for example, be on the order of and by the application of a suitable fonce the roller can easily be expanded into the illustrated condition. It should be understood that although the inner end of the wing roller has been illustrated as of a differing diameter this is not always necessary and under the circumstances it may be possible to form an outer end portion, or perhaps the entire wing roller, with an outwardly increasing differential diameter.

, The use and operation of the invention is as follows:

This invention provides means for automatically training the conveying reach of a conveyor belt in a belt conveyor system by setting up a differential drag between the belt and the rollers over which it passes. Various modifications of the invention are feasible but the basic principle underlying the invention can be illustrated best in connection with the embodiment of FIGURES 3 and 4.

In FIGURES 3 and 4, the contact pattern between the 'belt and the wing roller is indicated by a roughly piesh'aped polygon indicated by the letters ACca. The belt, which moves in a direction indicated at 49, is detrained to the right and makes contact with substantially the entire length of the right wing rollers 43, but only partially contacts left Wing roller 42. Somewhere along wing roller 43 a point on the belt will move over the roller at the same speed 'as a corresponding point on the roller. In other words, the linear speed of the belt at that point will be equal to the peripheral speed of the roller. Although the exact theory underlying the invention is not entirely understood at the present time, it is believed that the point of equal speed would be substantially closer to the inner end of the wing rollerthan to the outer end. The location of this condition of identical speed is indicated by the line bB. To the left of the line b3 the Ibelt moves slower than the surface of the Wing roller. At the extreme inner end of the roller, or at the line [2B the belt moves faster than the surface of the wing roller and this differential increases to a maximum at the outer end of the roller. This path of maximum differential is indicated by the line aA.

That portion of the :belt to the left of line Bb tends to drag the wing roller backward, that is upstream since the belt moves 'over the contact area BCcb at a speed less than the peripheral speed of the roller. That portion of the belt to the right of line Bb tends to drag the roller forward since the belt moves over the contact area BlmA at a speed greater than the peripheral speed of the roller. Since the area ABba is larger than area BCcb the effect of area ABba predominates and the wing roller is dragged forward whereby the entire roller assembly is rotated slight counter-clockwise. The training effect of the rollers on the belt is then effective in the direction of arrow 49a and the belt is urged toward center. As the belt moves back to a centered position the assembly moves back to a position substantially transverse to the direction of belt travel.

Basic to an understanding of the invention, of course, is the concept that a roller exerts a training effect on a belt passing over it in a direction substantially perpendicular to the longitudinal axis of the roller. By maintaining at least the wing rollers canted in the direction of belt travel, the tnaining effect continuously urges a detrained belt back towards a centered position.

Although only a single roller assembly has been illustrated, in actual practice a plurality of them may be connected into a belt conveyor system. It is not essential that each roller assembly be an automatic training assembly if the needed training effect can be obtained by .a fewer number of assemblies. In one practical embodiment, it was discovered that roller assemblies each having a training range of approximately two degrees in both the upstream and downstream direction did an excellent job of centering the belt. with substantially the same installation, one roller assembly in four having a training range on the order of about seven to eight degrees yielded substantially the equivalent effect of the continuous series of two degree training assemblies. At the same time it is quite feasible, when conditions require, that each training assembly have a training angle of approximately seven to eight degrees. An angle of inclination of even greater than eight degrees may be utilized but practical experience has indicated that such an extreme angle may set up frictional drag to the point that the horsepower requirements may be uneconomically increased. Further 'When the angle of taper is greater than about 8 the differential drag effect may be so pronounced that rubber belts will actually shred away or, more accurately, peel off, the supporting fabric. At the same time, although an angle of taper of even less than about 2 will have some effect an angle of about 2 will provide an effect which can be consistently relied upon. For these reasons the range of angle of taper of from about 2 up to about 8 is a preferred range of angle of taper.

Another important feature of the invention is that the rollers which exert the training effect upon the belt are those rollers which directly support only a very minor portion of the load. That is to say, experience has indicated that the center, or primary load carrying rollers should not be of differential diameter because of the very considerable frictionable force which would be generated thereby. It is nearly invariably preferable that the rollers which support only a minor portion of load, obviously usually the outermost wing rollers, exert the training effect. This is true of all the embodiments. In short the illustrated embodiments are especially suited for rubber belts, or belts having the characteristics of flexure and compressibility of rubber such as neoprene or plastic belts, because they impart an effective training effect to the belt at points at which the training effect will have the least detrimental effect on the belt.

It should also be noted that the slideways 32, 32a, are horizontal so that it is never necessary for the wing roller shafts to travel other than in a plane parallel to the plane of incline of the conveyor. When an unloaded belt is reversed there may be very slight contact between the wing rollers and the belt. The frictional drag of the belt on the rollers may not be sulficient to swing the rollers from one extreme to the other if the shafts must climb up and over a hump intermediate end positions. At the same time even though this emminently desirable feature is retained there is no danger of the wing roller shafts sliding back once they are properly in position because of the inherent training features of the specified angle of taper.

Another beneficial effect of my assembly is the fact that better contact results between a center roller and the belt in both empty and lightly loaded conditions. This results in better train-ing since the training effect varies to some extent with belt contact. It frequently happens that with the stiff belts often used in the coal mining industry for example bridging occurs between the wing and center rollers when they are of equal diameter. By decreasing the troughing angle a belt must take between the wing and center rollers the bridging effect is substantially reduced.

Although various embodiments of the invention have been disclosed it will be understood that the spirit of the invention is not limited to the precise showing illustrated and described herein. Accordingly, the scope of the invention should not be limited except by the scope of the appended claims when interpreted in light of the pertinent prior art.

We claim:

1. In a belt conveyor troughing idler assembly having an intermediate load carrying roller flanked by a pair of wing rollers, each wing roller having its outer end mounted for swinging movement to and fro about its inner end as a pivot whereby the wing rollers may be canted into a belt training position in response to passage thereover of a conveyor belt in a detrained condition, means for canting the roller in the direction of belt travel, said means including, for each wing roller, a tapered roller shell, the maximum cross sectional area of said tapered roller shell being located at the roller end closest to the intermediate roller, the angle of taper of the tapered roller shell being within the range of from about 2 to about 8 as measured with respect to the axis of rotationof the roller shell.

2. The belt conveyor troughing idler assembly of claim 1 further including means providing flexing movement of each wing roller with respect to its adjacent intermediate roller in a generally vertical plane.

References Cited by the Examiner UNITED STATES PATENTS 2,593,069 4/ 1952 Steinmetz. 2,688,216 9/1954 Lorig et al. l98202 2,815,851 12/1957 Yoshimura 198202 2,892,534 1/1959 Ogden 198202 3,002,606 10/1961 L0 Presti 198202 3,018,540 1/1962 Chavannes.

SAMUEL F. COLEMAN, Primary Examiner.

ERNEST A. FALLER, RICHARD E. AEGERTER,

Examiners. 

1. IN A BELT CONVEYOR TROUGHING IDLER ASSEMBLY HAVING AN INTERMEDIATE LOAD CARRYING ROLLER FLANKED BY A PAIR OF WING ROLLERS, EACH WING ROLLER HAVING ITS OUTER END MOUNTED FOR SWINGING MOVEMENT TO ANF FRO ABOUT ITS INNER END AS A PIVOT WHEREBY THE WIND ROLLERS MAY BE CANTED INTO A BELT TRAINING POSITION IN RESPONSE TO PASSAGE THEREOVER OF A CONVEYOR BELT IN A DETRAINED CONDITION, MEANS FOR CANTING THE ROLLER IN THE DIRECTION OF BELT TRAVEL, SAID MEANS INCLUDING, FOR EACH WING ROLLER, A TAPRERED ROLLER SHELL, THE MAXIMUM CROSS SECTIONAL AREA OF SAID TAPERED ROLLER SHELL BEING LOCATED AT THE ROLLER END CLOSEST TO THE INTERMEDIATE ROLLER, THE ANGLE TO TAPER OF THE TAPERED ROLLER SHELL BEING WITHIN THE RANGE OF FROM ABOUT 2* TO ABOUT 8* AS MEASURED WITH RESPECT TO THE AXIS OF ROTATION OF THE ROLLER SHELL. 